To explore the development status and safety of nuclear power

A nuclear power equipment industry overview

Nuclear power plant definition and classification

According to the reactor form, nuclear power plants are mainly divided into pressurized water reactor, boiling water reactor, heavy water reactor and fast reactor nuclear power plants, of which pressurized water reactor nuclear power plants are the most widely used, and the future is to develop fast reactor nuclear power plants with higher efficiency and safety.

A nuclear power plant is a facility that converts nuclear energy into electricity through appropriate devices. The third-generation nuclear power plant can be divided into light water reactors, heavy water reactors and fast neutron reactors according to the reactor form, of which light water reactors can be divided into pressurized water reactors and boiling water reactors according to the light water form.

Nuclear power equipment Introduction

The nuclear power equipment is divided into three parts: nuclear island, conventional island and auxiliary system, of which the nuclear island is the core of the entire nuclear power plant, responsible for converting nuclear energy into heat energy, the conventional island uses steam to generate electricity, and the auxiliary system is to ensure the smooth operation of the nuclear power plant.

Nuclear power equipment is divided into nuclear island, conventional island, BOP (other auxiliary equipment). The nuclear island is the core of the entire nuclear power plant, responsible for converting nuclear energy into heat energy, and is the most complex and costly part of the nuclear power plant. Conventional Island uses steam to drive steam turbines to drive engines to generate electricity. Auxiliary system (BOP) mainly includes digital control system, HVAC system, air cooling equipment and loading and unloading machine, which is used to ensure the smooth operation of nuclear power plant.

The core part of the nuclear island is the reactor, which is composed of core fuel, control rods and coolant. The core fission produces neutrons and energy, and the control rods are used to regulate the reactor power. The control rods are mainly composed of boron, which absorbs the neutrons produced in the reactor and regulates the power by adjusting the insertion of the control rods into the core fuel.

To prevent excessive heat in the reaction, light or heavy water is used as a coolant to reduce the temperature inside the reactor. The nuclear island structure of boiling water reactor is different from that of pressurized water reactor and heavy water reactor.

As shown in the figure, the cooling light water in the boiling water reactor nuclear power plant directly forms steam in the pressure vessel, and the pressurizer and evaporator need to be added to the pressurized water reactor and the heavy water reactor to form a second circuit.

Conventional island consists of steam turbine, generator and cooling system. The coolant converts the heat in the reactor into steam and sends it to the conventional island, where the steam drives the turbine to produce mechanical energy, which is transferred to the generator and converted into electrical energy. The steam drives the turbine and is transferred to the condenser where it is liquefied to form a new coolant.

China's nuclear power equipment industry chain

Industrial chain graph

The upstream of the nuclear power equipment industry chain is the raw materials required for production, the midstream is the nuclear island equipment, conventional island equipment and auxiliary equipment three types of nuclear power equipment, and the downstream is the operation of nuclear power plants, and the operation of nuclear power plants is in the monopoly of three state-owned enterprises.

Upstream analysis

The main cost of nuclear fuel comes from uranium, and our country is facing a shortage of uranium ore resources, highly dependent on resource imports, our government is through technology upgrading and overseas acquisition to solve the problem of external dependence is too high.

The core material of the nuclear fuel rod is the fuel pellet, composed of uranium dioxide, which is the main raw material for the heat generated by the fission reaction.

Uranium dioxide is extracted from natural uranium, and uranium ore needs to go through the process of exploration and exploitation, hydrometallurgy, uranium conversion and uranium enrichment, and finally sent to the nuclear fuel processing plant to manufacture nuclear fuel elements. In the nuclear fuel cost structure, natural uranium accounts for the highest proportion, reaching 49%.

Chinese companies engaged in uranium mining and import and export are required to obtain a government license, and only CNNC and CGN are qualified to engage in such business.

Due to the high technical difficulty and national security significance of nuclear fuel element development, nuclear fuel manufacturing in China is monopolized by CNNC North Nuclear Fuel Element Co., Ltd. and CNNC Jianzhong Fuel Element Co., LTD., which are owned by CNNC Group, and nuclear fuel element enterprises have strong bargaining power.

Most of China's uranium resources belong to unconventional uranium, low grade, deep burial, and expensive mining costs, so China's uranium resources production is low, can not meet its own nuclear power development needs, supply and demand imbalance, can only rely on imports. In 2017, the external dependence of uranium resources in China was as high as 85.9%, far exceeding the international warning line of 50%.